FAT32 – Same as File Allocation Table – (FAT or FAT32) DOS put the FAT into use to control the disk data area. The FAT directs DOS about the portions of the disk that belong to each file. The FAT not only link all of the clusters belonging to each file together, it does so without worrying about their position on disk. The FAT is a very significant file: there is a serious need to back it up on a regular basis.